The present invention relates to a cylinder apparatus for a rotary printing press which adjusts throw-on and throw-off of cylinders in contact opposite to each other, and the skew of a cylinder.
In various types of multicolor rotary printing presses such as an offset printing press, if plates mounted on the plate cylinders are misregistered among printing units of a plurality of ink colors, the images of the respective ink colors are printed misregistered. In view of this problem, a cylinder apparatus for a rotary printing press of this type has a plate registration unit for adjusting register of plates. U.S. Pat. No. 5,311,817 (reference 1) discloses a cylinder apparatus for a rotary printing press of this type. According to U.S. Pat. No. 5,311,817, both end shafts of a plate cylinder 66 are rotatably supported by the right and left frames 51 through the eccentric bearings 67, and the piston rods 70 of the cylinders 69 are connected to the eccentric bearings 67. The plate cylinder 66 is moved into contact with, and away from, the rubber blanket cylinders 53 by rotating the eccentric bearings 67 by making the piston rods 70 move forward and backward. Further, the eccentric cam 71 restricting the amount of revolution of the eccentric bearing 67 rotates by operating together with the position adjustment of the rubber blanket cylinder 53 when the thickness of a sheet is changed. As a result, the printing pressure of the rubber blanket cylinder 53 and the plate cylinder 66 becomes constant, regardless of the position of the rubber blanket cylinder 53.
The object of the present invention is to provide a drum unit of a rotary printing press, which has improved the printing quality by preventing clattering of a plate cylinder during the printing operation, by enabling to make a twist adjustment.
However, according to such a conventional unit, there has been a problem of not being able to make a plate registration by moving and adjusting one minor axis only of a plate cylinder, which is a so-called twisting adjustment.
It is an object of the present invention to provide a cylinder apparatus for a rotary printing press which improves printing quality.
In order to achieve the above object, according to the present invention, there is provided a cylinder apparatus for a rotary printing press, comprising a pair of first eccentric bearings for rotatatively supporting two ends of at least one first cylinder, the first eccentric bearings having abutting portions, a second eccentric bearing for pivotally supporting one of the first eccentric bearings, a pair of support members arranged to oppose each other through a predetermined distance and adapted to pivotally support the second eccentric bearing and the other one of the first eccentric bearings, a pair of first driving means for pivoting the first eccentric bearings supported by one of the support members and the second eccentric bearing, second driving means for pivoting the second eccentric bearing supported by the other one of the support members, and a pair of abutting members which are supported by the support members and against which the abutting portions of the first eccentric bearings abut when the first cylinder abuts against a second cylinder upon driving operation of the first driving means.